I'm curious if anyone has worked up an automated (or semi-automated) system and specifically which broker they chose. I have the programming skills to interact with most systems. I've got some basic entry/exits working with TradeStation (but generally find it hacky & annoying to insert Strategies into Charts) and have briefly looked at TWS's API. I've built stop monitoring systems & order parsing from TradingBlox's generated orders. I just need a reliable way to execute the orders.

What I'd really love is an API (SOAP/RESTful preferred) that allows me to place orders, check on order status & maybe get quotes... without running a platform.

RJ O'Brien has RJO Connect (which I'm guessing is a raw FIX API?) and after some Googling there are hints at XMLRPC methods.